There has been developed a control system for an in-cylinder injection internal combustion engine that has a fuel injection valve that injects fuel into a cylinder, a high pressure pump that boosts the pressure of fuel pumped up from a fuel tank, a high pressure fuel passage for supplying fuel discharged from the high pressure pump to the fuel injection valve, fuel pressure estimation means for estimating the fuel pressure in the high pressure fuel passage by model calculation, a fuel pressure sensor that measures the fuel pressure in the high pressure fuel passage, and failure determination means for determining that a high pressure fuel system ranging from the high pressure pump to the fuel injection valve is in failure when the difference between the fuel pressure estimated by the fuel pressure estimation means and the fuel pressure measured by the fuel pressure sensor exceeds an error range (see, for example, Patent Document 1).
In a technology described in Patent Document 2, in an internal combustion engine equipped with a low pressure fuel pump that pumps up fuel from a fuel tank and a high pressure fuel pump that boosts the pressure of fuel discharged from the low pressure fuel pump, the high pressure pump is controlled by open control and a closed loop control value, and it is determined that cavitation occurs in the second pump when the control value exceeds a limit value.
In a technology disclosed in Patent Document 3, a failure in a high pressure fuel pump is detected based on a change in the pressure of fuel discharged from the high pressure fuel pump at the time when an electromagnetic spindle valve of the high pressure fuel pump is actuated.
In the technology described in Patent Document 4, in an internal combustion engine equipped with a low pressure fuel pump that pumps up fuel from a fuel tank and a high pressure fuel pump that boosts the pressure of fuel discharged from the low pressure fuel pump, if the duty cycle of the high pressure fuel pump is not smaller than a predetermined value, the discharge pressure (or feed pressure) of the low pressure fuel pump is raised.